This application relates to a storm drain filter system which is placed beneath the grate of the entrance to a storm water catch basin and especially to a filter system which collects the entering storm water and filters out hydrocarbons, such as automobile oil, sand and debris, from the storm water to provide cleaner water to a storm drain pipe.
Ground water from heavy rains or melted snow is collected in storm sewer catch basins and flows into an underground storm drain or sewer line. The water flows into the basin through openings in a grate placed on top of the basin to prevent larger solids from entering the basin. Conventional storm sewer filters remove solids from the water before the water flows into the catch basin. These filters are sometimes made of a porous material and located at or above grade level. Filters may be placed horizontally on top of the grate or may be positioned vertically in a circle above grade level surrounding the grate. Water flows through the filter and into the catch basin while solids are captured by the filter.
One prior art U.S. patent for a storm sewer filter can be seen in the Logue, Jr. U.S. Pat. No. 5,575,925, for a storm sewer catch basin and filter having a removable filter for buried catch basins. The filter includes a bag located below grade level in the catch basin and looped flaps which extend above grade level to aid in the removal of the filter from the catch basin. The filter is held in place in the basin by a heavy grate which rests on top of the flaps. In the Webb U.S. Pat. No. 5,192,156, a drain apparatus for a liquid trap is provided for placement in the opening for catching a runoff liquid from a surface into a sewer through a passageway extending between the surface and the sewer and for forming a liquid barrier between the sewer and the surface to prevent the flow of gases from the sewer to the surface. The Shyh U.S. Pat. No. 5,284,580, is a refuge collecting frame for a drainage sewer which is placed beneath a cover of a sewer drainage opening to accumulate refuge and permit easy disposable of the refuge accumulated therein to prevent blockage of the sewer. The frame body is a rectangular frame structure having dimensions corresponding to the opening of a sewer drain and has a filtering net or porous board with a plurality of holes therein incorporated into each side and bottom of the frame. The Tharp U.S. Pat. No. 5,632,889, is a filter cartridge for separating liquid hydrocarbons from water. A cartridge is formed from perlite particles which have been expanded and treated. The cartridge is mounted and removed from a catch basin opening. The Sewell U.S. Pat. No. 5,650,065, is a skimmer cover for a dry well in a catch basin for placing in an opening in a storm water catch basin to prevent floatable materials, such as hydrocarbons from a motor vehicle, from entering the catch basin. The Billias et al. U.S. Pat. No. 5,643,445, is a removable storm water screen and overflow device which includes a debris removing screen basket and overflow apparatus for use in a storm collection sewer and includes a central panel with foldable wings in each side of the central panel and in which each wing can have an optional extension panel slidably attached to each wing by bolts and nuts through longitudinal slots.
The prior U.S. Pat. to Happel, No. 6,270,663, is for a storm drain filter system which is placed beneath the grate of the entrance to a storm water catch basin and especially to a filter system which collects the entering storm water and filters out hydrocarbons, such as automobile oil, sand and debris, such as grass clippings, from the storm water to provide a cleaner water to the storm pipe by passing the drainage water onto an oil filter boom and then into a container having fine screen filtered outlets in the bottom and coarser screen filters on the sides and having overflow openings near the top of the container.